Information recording medium information recording method and information recording/reproduction system

ABSTRACT

An information recording medium including a plurality of sectors of the present invention includes: a first spare area including a spare sector for replacing a defective sector among the plurality of sectors; a defect management information area for managing the replacement of the defective sector by the spare sector; and a volume space in which user data can be recorded. The volume space is configured so that a second spare area including a spare sector for replacing a defective sector among the plurality of sectors can be additionally allocated. Location information indicating a location of the second spare area is recorded in the defect management information area.

This application is a continuation of U.S. Ser. No. 09/494,594, filedJan. 31, 2000 U.S. Pat. No. 6,581,167.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information recording medium, aninformation recording method and an information recording/reproductionsystem, in which it is possible to increase the reliability of datarecording by dynamically extending the spare area according to thefrequency of occurrence of defective sectors.

2. Description of the Related Art

An optical disk is a type of information recording medium which has asector structure. In recent years, as the recording density and thecapacity of an optical disk have been increased, it has become moreimportant to ensure the reliability thereof.

Conventionally, a defect management method is known in the art formanaging defective sectors on the optical disk (i.e., sectors whichcannot be used for recording/reproduction of data). A spare area isprovided in advance on the optical disk. When there is a defectivesector on the optical disk, the defective sector is replaced by anothersector in the spare area. Thus, the reliability of the optical disk isensured. Such a defect management method is described in InternationalStandards Organization ISO/IEC 10090 for 90 mm optical disks.

The conventional defect management method described in the InternationalStandards Organization ISO/IEC 10090 for 90 mm optical disks will now beoutlined with reference to FIGS. 12 and 13.

FIG. 12 illustrates a structure of a data recording area 800 of aconventional optical disk.

The data recording area 800 includes a plurality of sectors. Each of theplurality of sectors is assigned a physical sector number (hereinafter,referred to as a “PSN”).

The data recording area 800 includes a defect management informationarea 801, a spare area 802 and a volume space 800 a. The volume space800 a is arranged immediately after the spare area 802, and is definedas an area in which user data can be recorded. Each of the sectorsincluded in the volume space 800 a is assigned a logical sector number(hereinafter, abbreviated as an “LSN”).

The size of the spare area 802 is predetermined. In order to change thesize of the spare area 802, it is necessary to change the data structureof the replacement information stored in the defect managementinformation area 801 by using a special command with physical formatutility software. This operation will hereinafter be referred to as aninitialization operation.

FIG. 13 illustrates a procedure of a conventional format operation and aconventional data write operation. These operations are performed by asystem control apparatus and an optical disk drive apparatus. Theoptical disk drive apparatus is connected to the system controlapparatus. The system control apparatus is, for example, a computersystem.

The format operation includes steps S901-S903 illustrated in FIG. 13.The data write operation includes steps S904-S911. In FIG. 12, eachreference numeral that starts with “S” beside an arrow denotes arecording operation corresponding to a step illustrated in FIG. 13.

When an optical disk is inserted into the optical disk drive apparatus,the optical disk drive apparatus reads out the defect managementinformation area 801 and recognizes replacement information whichindicates that a defective sector has been replaced by a spare sector(step S901).

The system control apparatus performs a FAT/root directory creationoperation, issues a Write command and transmits data to the optical diskdrive apparatus (step S902).

The optical disk drive apparatus uses format utility software torecognize the physical structure of the optical disk and records thedata transmitted from the system control apparatus from the beginning ofthe volume space 800 a (step S903). As a result, a FAT area 803 and aroot directory area 804 are arranged starting from the beginning of thevolume space 800 a. Such a logical format operation is similar to theformat operation for a file system in a MS-DOS format. As a result, thearea from immediately after the root directory area 804 to the end ofthe optical disk is handled as a file data space 800 b which is managedby the FAT.

A data write operation for recording data (File-a) under the rootdirectory will now be described.

The system control apparatus performs a recording operation for the data(File-a), issues a Write command and transmits data to the optical diskdrive apparatus (step S904). The location at which the data should berecorded is specified by an LSN.

The optical disk drive apparatus records the data transmitted from thesystem control apparatus in a sector which is assigned the specified LSN(step S905). Whether or not the data has been correctly recorded isdetermined by reading out the recorded data and by comparing the readdata with the transmitted data. When the data has not been correctlyrecorded, the sector which is assigned the specified LSN is detected asa defective sector. The defective sector occurs mainly due to dirt ordust attached to the optical disk.

For example, assume a case where sector b (sector 814) illustrated inFIG. 12 has been detected as a defective sector. In such a case, theoptical disk drive apparatus records the data which is supposed to berecorded in the defective sector 814 in #1 spare sector 810 of the sparearea 802, generates, as defect management information, #1 replacemententry 832 which indicates that the defective sector 814 has beenreplaced by the #1 spare sector 810, and records the #1 replacemententry 832 in the defect management information area 801 (step S906).

The #1 replacement entry 832 includes location information 833indicating the location of the defective sector and location information834 indicating the location of the spare sector by which it is replaced.Each of the location information 833 and 834 is represented by a PSN.

When the system control apparatus instructs the optical disk driveapparatus to read out data from the defective sector 814, the opticaldisk drive apparatus performs address conversion with reference to the#1 replacement entry 832 and reads out the data from the #1 spare sector810.

Thus, by replacing a defective sector by a spare sector, it is possibleto ensure the reliability of the optical disk. Moreover, since suchdefective sector replacement operation is performed by the optical diskdrive apparatus, it is possible to ensure that the system controlapparatus always records data at a location corresponding to thespecified LSN. As a result, the system control apparatus can handle theoptical disk as a defect-free medium.

Then, the system control apparatus performs a root directory recordingoperation, issues a Write command and transmits data to the optical diskdrive apparatus (step S907).

The optical disk drive apparatus updates root directory informationrecorded in the root directory area 804 according to the datatransmitted from the system control apparatus (step S908).

The system control apparatus performs a FAT recording operation, issuesa Write command and transmits data to the optical disk drive apparatus(step S909).

The optical disk drive apparatus updates FAT information recorded in theFAT area 803 according to the data transmitted from the system controlapparatus (step S910). Thus, the data (File-a) is registered under theroot directory.

The optical disk drive apparatus records the updated defect managementinformation in the defect management information area 801. Suchrecording is performed when there is no data recording instruction fromthe system control apparatus for a few seconds.

In the above-described conventional defect management method, the sizeof a spare area is fixed. Therefore, if there occurs defective sectorsbeyond the size of the replacement area, data cannot be recorded on theoptical disk even when an unallocated area available for recording stillexists on the optical disk. In order to record data on the optical disk,it is necessary to change the size of the spare area by performinganother initialization operation on the optical disk. In such a case,data recorded in the volume space needed to be backed up on anothermedium before performing the initialization operation because the LSNallocation would be changed over the entire area of the volume space.

Especially, in a case where an optical disk is used with consumerequipment, the user may handle the optical disk while eating food or achild may inadvertently touch the surface of the optical disk, wherebymore defective sectors may occur on the optical disk than expected bythe manufacturer.

SUMMARY OF THE INVENTION

According to one aspect of this invention, an information recordingmedium including a plurality of sectors includes: a first spare areaincluding a spare sector for replacing a defective sector among theplurality of sectors; a defect management information area for managingthe replacement of the defective sector by the spare sector; and avolume space in which user data can be recorded. The volume space isconfigured so that a second spare area including a spare sector forreplacing a defective sector among the plurality of sectors can beadditionally allocated. Location information indicating a location ofthe second spare area is recorded in the defect management informationarea.

In one embodiment of the invention, the second spare area is allocatedin an area separated from the first spare area.

In one embodiment of the invention, the second spare area is allocatedin an area contiguous with the first spare area.

In one embodiment of the invention, each of the first spare area and thesecond spare area is assigned physical sector numbers. The physicalsector numbers assigned to the first spare area are smaller than thephysical sector numbers assigned to the second spare area.

In one embodiment of the invention, the second spare area includes aplurality of spare sectors. Each of the plurality of spare sectors isassigned a physical sector number. The defective sector is replaced byone of the plurality of spare sectors in descending order of thephysical sector numbers respectively assigned to the plurality of sparesectors.

In one embodiment of the invention, the second spare area can beextended in a direction along which the physical sector numberdecreases.

In one embodiment of the invention, the second spare area is allocatedoutside the volume space.

In one embodiment of the invention, the second spare area is allocatedinside the volume space. The location information indicating thelocation of the second spare area is recorded in a basic file structuremanagement area for managing a basic file structure.

According to another aspect of this invention, an information recordingmedium including a plurality of sectors includes: a first spare areaincluding a spare sector for replacing a defective sector among theplurality of sectors; a defect management information area for managingthe replacement of the defective sector by the spare sector; and avolume space in which user data can be recorded. The volume space isconfigured so that a second spare area including a spare sector forreplacing a defective sector among the plurality of sectors can beadditionally allocated. Information indicating an amount of spare areaavailable in the first spare area and information indicating an amountof spare area available in the second spare area are recorded in thedefect management information area.

In one embodiment of the invention, the information of the amount ofspare area available in the first spare area includes a replacemententry which indicates that the defective sector has been replaced by aspare sector in the first spare area. The information of the amount ofspare area available in the second spare area includes a size of thesecond spare area and a replacement entry which indicates that thedefective sector has been replaced by a spare sector in the second sparearea.

In one embodiment of the invention, the information of the amount ofspare area available in the first spare area includes a first full flagwhich indicates whether or not there is any spare sector available inthe first spare area. The information of the amount of spare areaavailable in the second spare area includes a second full flag whichindicates whether or not there is any spare sector available in thesecond spare area.

According to still another aspect of this invention, there is providedan information recording method for recording information on aninformation recording medium including a plurality of sectors. Theinformation recording medium includes: a first spare area including aspare sector for replacing a defective sector among the plurality ofsectors; a defect management information area for managing thereplacement of the defective sector by the spare sector; and a volumespace in which user data can be recorded, wherein the volume space isconfigured so that a second spare area including a spare sector forreplacing a defective sector among the plurality of sectors can beadditionally allocated. The information recording method includes thesteps of: (a) obtaining information which indicates a status ofconsumption of the first spare area; (b) determining whether or not toadditionally allocate the second spare area according to the informationwhich indicates the status of consumption of the first spare area; (c)when it is determined to additionally allocate the second spare area,making a part of the volume space available as the second spare area;and (d) recording information indicating a location of the second sparearea in the defect management information area.

In one embodiment of the invention, a first full flag which indicateswhether or not there is any spare sector available in the first sparearea is recorded in the defect management information area. The step (a)includes the step of determining whether or not there is any sparesector available in the first spare area by referencing the first fullflag.

In one embodiment of the invention, a replacement entry which indicatesthat the defective sector has been replaced by a spare sector in thefirst spare area is recorded in the defect management information area.The step (a) includes the step of determining whether or not there isany spare sector available in the first spare area by referencing thereplacement entry.

In one embodiment of the invention, the step (c) includes the steps of:(c-1) reducing the volume space: and (c-2) allocating an area on anouter periphery side following the reduced volume space as the secondspare area.

In one embodiment of the invention, the step (c) includes the step ofallocating a part of a logical volume space of the volume space as thesecond spare area.

In one embodiment of the invention, the step (c) includes the step ofmoving data recorded in a part of a logical volume space of the volumespace to another part of the logical volume space, and then allocatingthe part of the logical volume space as the second spare area.

In one embodiment of the invention, the step (d) includes the step of,before recording the information indicating the location of the secondspare area in the defect management information area, detecting adefective sector in the part of the volume space made available.

In one embodiment of the invention, the second spare area is allocatedin an area separated from the first spare area.

In one embodiment of the invention, the second spare area is allocatedin an area contiguous with the first spare area.

In one embodiment of the invention, each of the first spare area and thesecond spare area is assigned physical sector numbers. The physicalsector numbers assigned to the first spare area are smaller than thephysical sector numbers assigned to the second spare area.

In one embodiment of the invention, the second spare area includes aplurality of spare sectors. Each of the plurality of spare sectors isassigned a physical sector number. The defective sector is replaced byone of the plurality of spare sectors in descending order of thephysical sector numbers respectively assigned to the plurality of sparesectors.

In one embodiment of the invention, the second spare area can beextended in a direction along which the physical sector numberdecreases.

According to still another aspect of this invention, there is providedan information recording method for recording information on aninformation recording medium including a plurality of sectors. Theinformation recording medium includes: a first spare area including aspare sector for replacing a defective sector among the plurality ofsectors; a defect management information area for managing thereplacement of the defective sector by the spare sector; and a volumespace in which user data can be recorded, wherein the volume space isconfigured so that a second spare area including a spare sector forreplacing a defective sector among the plurality of sectors can beadditionally allocated. The information recording method includes thesteps of: (a) obtaining information which indicates a status ofconsumption of the second spare area; (b) determining whether or not toadditionally allocate the second spare area according to the informationwhich indicates the status of consumption of the second spare area; (c)when it is determined to additionally allocate the second spare area,making a part of the volume space available as the second spare area;and (d) recording information indicating a location of the second sparearea in the defect management information area.

In one embodiment of the invention, a second full flag which indicateswhether or not there is any spare sector available in the second sparearea is recorded in the defect management information area. The step (a)includes the step of determining whether or not there is any sparesector available in the second spare area by referencing the second fullflag.

In one embodiment of the invention, a replacement entry which indicatesthat the defective sector has been replaced by a spare sector in thesecond spare area is recorded in the defect management information area.The step (a) includes the step of determining whether or not there isany spare sector available in the second spare area by referencing thereplacement entry.

In one embodiment of the invention, the step (c) includes the steps of:(c-1) reducing the volume space; and (c-2) allocating an area on anouter periphery side following the reduced volume space as the secondspare area.

In one embodiment of the invention, the step (c) includes the step ofallocating a part of a logical volume space of the volume space as thesecond spare area.

In one embodiment of the invention, the step (c) includes the step ofmoving data recorded in a part of a logical volume space of the volumespace to another part of the logical volume space, and then allocatingthe part of the logical volume space as the second spare area.

In one embodiment of the invention, the step (d) includes the step of,before recording the information indicating the location of the secondspare area in the defect management information area, detecting adefective sector in the part of the volume space made available.

In one embodiment of the invention, the step (d) includes the step ofresetting a second full flag which indicates whether or not there is anyspare sector available in the second spare area, after recording theinformation indicating the location of the second spare area in thedefect management information area.

In one embodiment of the invention, the second spare area is allocatedin an area separated from the first spare area.

In one embodiment of the invention, the second spare area is allocatedin an area contiguous with the first spare area.

In one embodiment of the invention, each of the first spare area and thesecond spare area is assigned physical sector numbers. The physicalsector numbers assigned to the first spare area are smaller than thephysical sector numbers assigned to the second spare area.

In one embodiment of the invention, the second spare area includes aplurality of spare sectors. Each of the plurality of spare sectors isassigned a physical sector number. The defective sector is replaced byone of the plurality of spare sectors in descending order of thephysical sector numbers respectively assigned to the plurality of sparesectors.

In one embodiment of the invention, the second spare area can beextended in a direction along which the physical sector numberdecreases.

According to still another aspect of this invention, there is providedan information recording/reproduction system for an informationrecording medium including a plurality of sectors. The informationrecording medium includes: a first spare area including a spare sectorfor replacing a defective sector among the plurality of sectors; adefect management information area for managing the replacement of thedefective sector by the spare sector; and a volume space in which userdata can be recorded, wherein the volume space is configured so that asecond spare area including a spare sector for replacing a defectivesector among the plurality of sectors can be additionally allocated. Theinformation recording/reproduction system includes: a remaining sparearea amount detection section for obtaining information indicating astatus of consumption of the first spare area; a spare area extensiondetermination section for determining whether or not to additionallyallocate the second spare area according to the information indicatingthe status of consumption of the first spare area; a spare extensionarea allocation section for, when it is determined to additionallyallocate the second spare area, making a part of the volume spaceavailable as the second spare area; and a spare area allocation sectionfor recording location information indicating a location of the secondspare area in the defect management information area.

In one embodiment of the invention, a first full flag which indicateswhether or not there is any spare sector available in the first sparearea is recorded in the defect management information area. Theremaining spare area amount detection section determines whether or notthere is any spare sector available in the first spare area byreferencing the first full flag.

In one embodiment of the invention, a replacement entry which indicatesthat the defective sector has been replaced by a spare sector in thefirst spare area is recorded in the defect management information area.The remaining spare area amount detection section determines whether ornot there is any spare sector available in the first spare area byreferencing the replacement entry.

In one embodiment of the invention, the spare extension area allocationsection reduces the volume space, and allocates an area on an outerperiphery side following the reduced volume space as the second sparearea.

In one embodiment of the invention, the spare extension area allocationsection allocates a part of a logical volume space of the volume spaceas the second spare area.

In one embodiment of the invention, the spare extension area allocationsection moves data recorded in a part of a logical volume space of thevolume space to another part of the logical volume space, and thenallocates the part of the logical volume space as the second spare area.

In one embodiment of the invention, the second spare area is allocatedin an area separated from the first spare area.

In one embodiment of the invention, the second spare area is allocatedin an area contiguous with the first spare area.

In one embodiment of the invention, each of the first spare area and thesecond spare area is assigned physical sector numbers. The physicalsector numbers assigned to the first spare area are smaller than thephysical sector numbers assigned to the second spare area.

In one embodiment of the invention, the second spare area includes aplurality of spare sectors. Each of the plurality of spare sectors isassigned a physical sector number. The defective sector is replaced byone of the plurality of spare sectors in descending order of thephysical sector numbers respectively assigned to the plurality of sparesectors.

In one embodiment of the invention, the second spare area can beextended in a direction along which the physical sector numberdecreases.

In one embodiment of the invention, the informationrecording/reproduction system includes a recording apparatus forrecording information on the information recording medium and a controlapparatus for controlling the recording apparatus. The recordingapparatus includes a remaining spare amount reporting section forreporting to the control apparatus information indicating a status ofconsumption of the first spare area which is obtained from the remainingspare area amount detection section.

In one embodiment of the invention, the information indicating thestatus of consumption of the first spare area includes informationindicating a remaining amount of the first spare area.

In one embodiment of the invention, the information indicating thestatus of consumption of the first spare area includes informationindicating an error status in response to a data recording instruction.

According to still another aspect of this invention, there is providedan information recording/reproduction system for an informationrecording medium including a plurality of sectors. The informationrecording medium includes: a first spare area including a spare sectorfor replacing a defective sector among the plurality of sectors; adefect management information area for managing the replacement of thedefective sector by the spare sector; and a volume space in which userdata can be recorded, wherein the volume space is configured so that asecond spare area including a spare sector for replacing a defectivesector among the plurality of sectors can be additionally allocated. Theinformation recording/reproduction system includes: a remaining sparearea amount detection section for obtaining information indicating astatus of consumption of the second spare area; a spare area extensiondetermination section for determining whether or not to additionallyallocate the second spare area according to the information indicatingthe status of consumption of the second spare area; a spare extensionarea allocation section for, when it is determined to additionallyallocate the second spare area, making a part of the volume spaceavailable as the second spare area; and a spare area allocation sectionfor recording location information indicating a location of the secondspare area in the defect management information area.

In one embodiment of the invention, a second full flag which indicateswhether or not there is any spare sector available in the second sparearea is recorded in the defect management information area. Theremaining spare area amount detection section determines whether or notthere is any spare sector available in the second spare area byreferencing the second full flag.

In one embodiment of the invention, a replacement entry which indicatesthat the defective sector has been replaced by a spare sector in thesecond spare area is recorded in the defect management information area.The remaining spare area amount detection section determines whether ornot there is any spare sector available in the second spare area byreferencing the replacement entry.

In one embodiment of the invention, the spare extension area allocationsection reduces the volume space, and allocates an area on an outerperiphery side following the reduced volume space as the second sparearea.

In one embodiment of the invention, the spare extension area allocationsection allocates a part of a logical volume space of the volume spaceas the second spare area.

In one embodiment of the invention, the spare extension area allocationsection moves data recorded in a part of a logical volume space of thevolume space to another part of the logical volume space, and thenallocates the part of the logical volume space as the second spare area.

In one embodiment of the invention, the spare extension area allocationsection resets a second full flag which indicates whether or not thereis any spare sector available in the second spare area, after recordingthe information indicating the location of the second spare area in thedefect management information area.

In one embodiment of the invention, the second spare area is allocatedin an area separated from the first spare area.

In one embodiment of the invention, the second spare area is allocatedin an area contiguous with the first spare area.

In one embodiment of the invention, each of the first spare area and thesecond spare area is assigned physical sector numbers. The physicalsector numbers assigned to the first spare area are smaller than thephysical sector numbers assigned to the second spare area.

In one embodiment of the invention, the second spare area includes aplurality of spare sectors; each of the plurality of spare sectors isassigned a physical sector number; and the defective sector is replacedby one of the plurality of spare sectors in descending order of thephysical sector numbers respectively assigned to the plurality of sparesectors.

In one embodiment of the invention, the second spare area can beextended in a direction along which the physical sector numberdecreases.

In one embodiment of the invention, the informationrecording/reproduction system includes a recording apparatus forrecording information on the information recording medium and a controlapparatus for controlling the recording apparatus. The recordingapparatus includes a remaining spare amount reporting section forreporting to the control apparatus information indicating a status ofconsumption of the second spare area which is obtained from theremaining spare area amount detection section.

In one embodiment of the invention, the information indicating thestatus of consumption of the second spare area includes informationindicating a remaining amount of the second spare area.

In one embodiment of the invention, the information indicating thestatus of consumption of the second spare area includes informationindicating an error status in response to a data recording instruction.

Thus, the invention described herein makes possible the advantage ofproviding an information recording medium, an information recordingmethod and an information recording/reproduction system, in which it ispossible to increase the reliability of data recording by dynamicallyextending the spare area according to the frequency of occurrence ofdefective sectors.

This and other advantages of the present invention will become apparentto those skilled in the art upon reading and understanding the followingdetailed description with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a structure of a data recording area100 of an optical disk according to an embodiment of the presentinvention;

FIG. 2 is a block diagram illustrating a structure of an informationrecording/reproduction system 1 a according to an embodiment of thepresent invention;

FIG. 3 is a protocol chart illustrating a procedure of a formatoperation;

FIG. 4 is a diagram illustrating a structure of the data recording area100 of an optical disk after a format operation;

FIG. 5 is a protocol chart illustrating a procedure of a data writeoperation;

FIGS. 6A-6C are protocol charts illustrating an procedure of anoperation of determining whether or not it is necessary to extend afirst spare area 102;

FIG. 7 is a protocol chart illustrating a procedure of an operation ofextending the first spare area 102 and a second spare area 108;

FIG. 8 is a diagram illustrating a structure of the data recording area100 of an optical disk according to an embodiment of the presentinvention;

FIG. 9 is a protocol chart illustrating a procedure of a data writeoperation for recording a file on an optical disk;

FIG. 10 is a protocol chart illustrating a procedure of an operationwhich is performed when an optical disk is inserted into an optical diskdrive apparatus;

FIG. 11 is a diagram illustrating an operation of updating volumestructure areas 103 and 109 and a basic file structure area 104:

FIG. 12 is a diagram illustrating a structure of a data recording area800 of a conventional optical disk; and

FIG. 13 is a protocol chart illustrating a procedure of a conventionalformat operation and a conventional data write operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An information recording medium of the present invention includes afirst spare area including a spare sector for replacing a defectivesector, a defect management information area for managing replacement ofa defective sector by a spare sector, and a volume space in which userdata can be recorded.

The volume space is configured so that a second spare area including aspare sector for replacing a defective sector can be additionallyallocated. When all of the spare sectors provided in advance in thefirst spare area have been consumed by the defective sector replacementoperation, a part of the volume space is made available as a secondspare area. Thus, by additionally allocating the second spare area whennecessary, it is possible to ensure the defect-free property of theoptical disk even when there occurs more defective sectors than expectedby the manufacturer of the optical disk.

Location information indicating the location of the second spare area isrecorded in the defect management information area.

Embodiments of the present invention will now be described withreference to the drawings.

Embodiment 1 is an embodiment in which the second spare area isallocated inside the volume space by updating the file structure.Embodiment 2 is an embodiment in which the second spare area isallocated outside the volume space by updating the volume structure andthe file structure.

(Embodiment 1)

FIG. 2 illustrates a structure of an information recording/reproductionsystem 1 a according to an embodiment of the present invention. Theinformation recording/reproduction system 1 a records information on theinformation recording medium and reproduces information recorded on theinformation recording medium. The information recording medium may beany type of rewritable optical disk such as a DVD-RAM.

It is assumed in the following description that the informationrecording medium is a rewritable optical disk on/from which filesmanaged by a file structure defined in the ECMA167 standard can berecorded/reproduced by sectors. Hereinafter, such a rewritable opticaldisk will be referred to simply as an optical disk.

As illustrated in FIG. 2, the information recording/reproduction system1 a includes a system control apparatus 200 and an optical disk driveapparatus 204. The system control apparatus 200 and the optical diskdrive apparatus 204 are connected to each other via an I/O bus 203.

The system control apparatus 200 includes a system control section 201for processing file structure information and a memory circuit 202. Thesystem control section 201 may be implemented by, for example, amicroprocessor including a control program and a memory for storingoperation results.

The system control section 201 includes: a file structure operationsection 211 for performing a bit map operation for managing unallocatedareas in a logical volume space; a spare extension area detectionsection 212 for examining whether or not an area which is determined tobe allocated as an additional spare area has already been used; a filemoving operation section 213 for allocating an additional spare area bymoving a file recorded in the area which is determined to be allocatedas an additional spare area to another area; a spare extension areaallocation section 214 for registering an additional spare area in afile structure; a spare area extension determination section 215 fordetermining whether or not the spare area should be extended based onthe amount of spare area remaining: a command status operation section216 for recognizing whether or not a defective sector has been detectedduring data recording by the execution result of a Write command; and aspare extension area issue section 217 for directing a spare area to beextended for the optical disk drive apparatus 204 for updating thedefect management information.

The memory circuit 202 includes a file structure memory 221, a bit mapmemory 222, a data memory 223, and a spare area information memory 224for storing information indicating the amount of spare area remainingand information indicating the location of the spare area.

The optical disk drive apparatus 204 includes a drive control section205 for performing a defect management operation and controlling therecording/reproduction of data on/from the optical disk, and a memorycircuit 206. The drive control section 205 may be implemented by, forexample, a microprocessor including a control program and a memory forarithmetic operations.

The drive control section 205 includes: a remaining spare amountreporting section 231 for reporting the area size which can be replacedby the spare area; a spare area allocation section 232 for updatingdefect management information according to a spare area extensioncommand from the system control apparatus 200; a remaining spare areaamount detection section 233 for detecting the area which can bereplaced by the spare area based on a replacement entry of the defectmanagement information area; a defective sector operation section 234for allocating a defective sector detected during data recording by aspare sector of the spare area and recording data in the spare sector; adata write control section 235 for controlling recording of data to theoptical disk: and a data read control section 236 for controllingreproduction of data from the optical disk.

The memory circuit 206 includes a defect management information memory241 for storing the defect management information, and a data memory242.

A format operation performed on an optical disk according to the presentinvention will now be described with reference to FIGS. 1, 2, 3 and 4.

FIG. 4 illustrates a structure of the data recording area 100 of anoptical disk after the format operation.

The data recording area 100 includes a plurality of sectors. Each of theplurality of sectors is assigned a PSN.

The data recording area 100 includes a defect management informationarea 101, a first spare area 102 and a volume space 100 a.

Defect management information 130 is recorded in the defect managementinformation area 101. The defect management information 130 includes anSDL descriptor 131 for identifying SDL information, a spare area fullflag 132, location information 133 indicating the location of the secondspare area 108, and #1 replacement entry 134 indicating that a defectivesector has been replaced by a spare sector.

The spare area full flag 132 includes a first full flag 138 for thefirst spare area 102 and a second full flag 139 for the second sparearea 108. The first full flag 138 indicates whether or not there is anyspare sector available in the first spare area 102. The second full flag139, when it is reset, indicates that there is a spare sector availablein the second spare area 108. The second full flag 139, when it is set,indicates that there is no more spare sector available in the secondspare area 108 or that no second spare area 108 has been allocated.

Hereinafter, the location information 133 indicating the location of thesecond spare area 108 will be referred to simply as the “second sparearea location information 133”. The second spare area locationinformation 133 is represented by, for example, the PSN of the firstsector included in the second spare area 108 and the PSN of the lastsector included in the second spare area 108.

In the example illustrated in FIG. 4, the second spare area has not yetbeen allocated on the data recording area 100. In such a case, thesecond spare area location information 133 has a value (e.g., the NULLvalue) which indicates that “the second spare area has not yet beenallocated on the data recording area 100”.

In the example illustrated in FIG. 4, the number of replacement entriesincluded in the defect management information 130 is 1. The defectmanagement information 130 may include a number of replacement entriesequal to the number of spare sectors replacing defective sectors.Therefore, when the number of spare sectors replacing defective sectorsis N, the defect management information 130 may include #1-#Nreplacement entries. Herein, N is any integer. Each of the #1-#Nreplacement entries includes location information 136 indicating thelocation of the defective sector and location information 137 indicatingthe location of the spare sector replacing the defective sector. Each ofthe location information 136 and 137 is represented by, for example, aPSN.

The size of the first spare area 102 is fixed. In the exampleillustrated in FIG. 4, the first spare area 102 includes three sparesectors 110-112, i.e., #1 spare sector to #3 spare sector. Each of thespare sectors 110-112 is used to replace a defective sector. The numberof spare sectors included in the first spare area 102 is not limited to3. The first spare area 102 may include any number of spare sectors.

The volume space 100 a is arranged immediately after the first sparearea 102, and is defined as an area in which user data can be recorded.Each of the sectors included in the volume space 100 a is assigned alogical sector number. The volume space 100 a includes the volumestructure area 103, a logical volume space 100 b and the volumestructure area 109.

FIG. 3 illustrates a procedure of a format operation. The formatoperation is performed by the system control apparatus 200 and theoptical disk drive apparatus 204.

The format operation includes steps S301-S307 illustrated in FIG. 3. InFIG. 4, each reference numeral that starts with “S” beside an arrowdenotes a recording operation corresponding to a step illustrated inFIG. 3.

When the optical disk is inserted into the optical disk drive apparatus204, the defect management information 130 is read out from the defectmanagement information area 101. The defect management information 130is stored in the defect management information memory 241.

The defect management information 130 stored in the defect managementinformation memory 241 is referenced by the remaining spare amountreporting section 231 and the remaining spare area amount detectionsection 233, as will be described below.

The remaining spare area amount detection section 233 recognizes thelocation information of the first and second spare areas and the statusof consumption of the first and second spare areas (step S301). Thestatus of consumption of each spare area is recognized by, for example,retrieving one of the replacement entries recorded in the defectmanagement information area 101 that has the smallest addressinformation (e.g., the physical sector number) of a spare sector.

The file structure operation section 211 issues a Get Spare Info commandto the optical disk drive apparatus 204 in order to inquire as to thespare area information (step S302).

The remaining spare amount reporting section 231 reports the spare areainformation to the system control apparatus 200 based on the defectmanagement information 130 stored in the defect management informationmemory 241 (step S303). The spare area information includes the locationinformation 133 indicating the location of the second spare area. Thespare area information is stored in the spare area information memory224.

The file structure operation section 211 performs a volumestructure/basic file structure creation operation and issues a Writecommand and transmits data to the optical disk drive apparatus 204 (stepS304). The data is once stored in the file structure memory 221, andthen transferred from the file structure memory 221 to the data memory242.

The data write control section 235 records data stored in the datamemory 242 starting from the beginning of the volume space 100 a (i.e.,the sector assigned the LSN “0”) (step S305). As a result, the volumestructure area 103 and the basic file structure area 104 are allocatedstarting from the beginning of the volume space 100 a.

Although not shown in FIG. 4, an anchor volume descriptor pointer, avolume descriptor sequence, a file set descriptor, a file entry for thesystem stream directory and the system stream directory are recorded inthe volume structure area 103.

The basic file structure area 104 includes a space bit map area 113, afile entry area 114, a root directory area 115 and a file entry area116.

A space bit map is recorded in the space bit map area 113. The space bitmap is a string of bits which indicates the allocation status in eachsector of the logical volume space 100 b. By referencing the space bitmap, it is possible to examine the status of consumption of each sectorin the logical volume space 100 b.

The location information and management information for the rootdirectory area 115 are recorded in the file entry area 114.

The names of the files recorded under the root directory and thelocation information for the file entry of each of such files arerecorded in the root directory area 115.

A file entry specified by the system stream directory is recorded in thefile entry area 116. The location information of the stream of thesecond spare area to be registered in the system stream directory ismanaged by this file entry. The file entry includes a descriptor tag 141for identifying the file entry, a file attribute 142 and locationinformation 143 indicating the location of the second spare area 108.

Hereinafter, the location information 143 indicating the location of thesecond spare area 108 will be referred to simply as the “second sparearea location information 143”. The second spare area locationinformation 143 is represented by, for example, the LSN of the firstsector included in the second spare area 108 and the size of the secondspare area 108.

In the format operation, information equivalent to the second spare arealocation information 133 included in the defect management information130 is recorded in the file entry area 116 as the second spare arealocation information 143. In the example illustrated in FIG. 4, thesecond spare area location information 133 has the NULL value, asdiscussed above. Accordingly, the second spare area location information143 also has the NULL value.

Whether or not the data transmitted from the system control apparatus200 has been correctly recorded in the volume structure area 103 and thebasic file structure area 104 is determined by reading out the recordeddata and by comparing the read data with the transmitted data (i.e., thedata stored in the data memory 242). Such a determination is performedby the defective sector operation section 234.

For example, when the data transmitted from the system control apparatus200 is not correctly recorded in the root directory area 115, the rootdirectory area 115 is detected as a defective sector. In such a case,the defective sector operation section 234 replaces the root directoryarea 115 by one of the available spare sectors included in the firstspare area 102 that has the largest address (i.e., the #1 spare sector112). As a result, data which is supposed to be recorded in the rootdirectory area 115 is recorded in the #1 spare sector 112 of the firstspare area 102. Moreover, the defective sector operation section 234generates the #1 replacement entry 134 which indicates that the rootdirectory area 115 has been replaced by the #1 spare sector 112 andstores the #1 replacement entry 134 in the defect management informationmemory 241 (step S306).

The defective sector operation section 234 records the updated defectmanagement information 130 stored in the defect management informationmemory 241 in the defect management information area 101 (step S307).Such recording is performed immediately after step S306 or when there isno command to record the data from the system control apparatus 200 fora predetermined period of time (e.g., 5 seconds).

As described above, in the optical disk format operation, informationthat has consistency with the second spare area location information 133recorded in the defect management information area 101 is recorded inthe basic file structure area 104 as the second spare area locationinformation 143. By performing the above-described format operation on aused optical disk, it is possible to reuse the used optical disk. Thisis because even if all of the information in the volume space 100 a iserased, the information in the second spare area is stored in the defectmanagement information area 101.

The second spare area location information 143 is managed by the systemcontrol apparatus 200, and the second spare area location information133 is managed by the optical disk drive apparatus 204. It is necessaryto ensure that the location information 143 and 133 always haveconsistency with each other. Countermeasures which can be taken when theinformation 143 and 133 are not consistent with each other and a methodfor recovering the inconsistency between the information 143 and 133will be described later.

A data write operation of recording a file named “File-a” under the rootdirectory of a formatted optical disk will now be described withreference to FIGS. 1, 2 and 5.

FIG. 1 illustrates a structure of the data recording area 100 of theoptical disk after the data write operation.

FIG. 5 illustrates a procedure of the data write operation. The datawrite operation is performed by the system control apparatus 200 and theoptical disk drive apparatus 204.

The data write operation includes steps S401-S417 illustrated in FIG. 5.In FIG. 1, each reference numeral that starts with “S” beside an arrowdenotes a recording operation corresponding to a step illustrated inFIG. 5.

When the optical disk is inserted into the optical disk drive apparatus204, the same defect management information operation as that done inthe format operation is performed as a start-up operation for theoptical disk drive apparatus 204 (step S401).

The file structure operation section 211 issues a Read command to theoptical disk drive apparatus 204 as a start-up operation for the systemcontrol apparatus 200 (step S402).

The data read control section 236 reproduces data from the volumestructure area 103 and the basic file structure area 104 according tothe address specified by the Read command and transmits the reproduceddata to the file structure memory 221 (step S403).

The file structure operation section 211 analyzes the volume structureand the basic file structure based on the data transmitted to the filestructure memory 221. As a result, the file structure operation section211 recognizes the logical volume space 100 a based on the datareproduced from the volume structure area 103, recognizes the locationand the size of an unallocated area 107 based on the data reproducedfrom the space bit map area 113, recognizes the directory structurebased on the data reproduced from the root directory area 115, andrecognizes the second spare area location information 143 based on thedata reproduced from the file entry area 116 (step S402).

The file structure operation section 211 creates data of a file named“File-a” and stores the data in the data memory 223. Moreover, the filestructure operation section 211 creates data of a file entry and storesthe data in the file structure memory 221. The file structure operationsection 211 issues a Write command and each data to the optical diskdrive apparatus 204 (step S404). The Write command is used to recordeach data at the address of the unallocated area 107 recognized in stepS402.

The data stored in the data memory 223 and the data stored in the filestructure memory 221 are transmitted to the data memory 242. The datawrite control section 235 records the respective data transmitted in thedata memory 242 in a data area 105 and in a file structure area 106according to the addresses specified by the Write command (step S405).

The defective sector operation section 234 performs a replacementoperation by the same method as that described in the description of theformat operation. For example, assume a case where sector b (sector 118)illustrated in FIG. 1 has been detected as a defective sector. In such acase, the defective sector operation section 234 records the data, whichis supposed to be recorded in the defective sector 118, in #2 sparesector 111 of the first spare area 102, generates #2 replacement entry135 which indicates that the defective sector 118 has been replaced bythe #2 spare sector 111, and records the #2 replacement entry 135 in thedefect management information memory 241 (step S406).

In order to register the file (File-a) under the root directory, it isnecessary to update the data recorded in the root directory area 115.The file structure operation section 211 issues the Write command andtransmits the data to the optical disk drive apparatus 204 (step S407).

The data write control section 235 references the #1 replacement entry134, converts the address of the root directory area 115 specified bythe Write command to the address of the #1 spare sector 112, and recordsthe data transmitted from the system control apparatus 200 in the #1spare sector 112 (step S408).

The spare area extension determination section 215 determines, based onthe status of consumption of the first spare area 102, whether or not itis necessary to extend the first spare area 102. There are variousmethods for such a determination. The details of such various methodswill later be described with reference to FIGS. 6A-6C.

Herein, an example of such determination methods will be described. Forexample, the spare area extension determination section 215 issues a GetEvent Status Notification command to the optical disk drive apparatus204. This command is used to inquire as to the status of consumption ofthe first spare area 102. In response to this inquiry, the spare areaextension determination section 215 determines that it is necessary toextend the first spare area 102 when the optical disk drive apparatus204 reports shortage information which indicates that the remainingamount of the first spare area 102 is less than a predetermined size(e.g., 1 MB) (step S409).

In response to the command issued from the system control apparatus 200in step S409, the remaining spare area amount detection section 233calculates the remaining amount of the first spare area 102 (e.g., thenumber of spare sectors in the first spare area 102 that are availablefor replacement) based on the information of the replacement entrystored in the defect management information memory 241. If the remainingamount is less than the predetermined size, the remaining spare areaamount detection section 233 instructs the remaining spare amountreporting section 231 to report the shortage information to the systemcontrol apparatus 200. The remaining spare amount reporting section 231reports the shortage information to the system control apparatus 200(step S410).

In the example illustrated in FIG. 1, the defective sector 118 isdetected when recording data in the data area 105, and the #2 sparesector 111 is used to replace the defective sector 118. Therefore, the#3 spare sector 110 is the only spare sector in the first spare area 102that is available for replacement. Then, if another defective sectoroccurs, the first spare area 102 would be exhausted, whereby no morereplacement operation can be done. Therefore, the remaining spare amountreporting section 231 reports the shortage information to the systemcontrol apparatus 200.

In order to enlarge spare area, it is necessary to update the file entryarea 116, the location information 133 indicating the location of thesecond spare area 108, and the space bit map area 113.

The system control apparatus 200 recognizes the unallocated area 107based on the data reproduced from the space bit map area 113 anddetermines the area to be reserved as an additional spare area (i.e.,the area where the second spare area 108 is allocated). The systemcontrol apparatus 200 updates the data stored in the file structurememory 221 in order to register the extended spare area, and updates thedata stored in the bit map memory 222 so that the sectors of the areawhere the second spare area 108 is to be allocated are indicated as“allocated”.

The system control apparatus 200 issues a Write command and transmitsthe data for the file entry area 116 stored in the file structure memory221 to the optical disk drive apparatus 204 (step S411).

The optical disk drive apparatus 204 updates the file entry area 116 byrecording the data transmitted from the system control apparatus 200 inthe file entry area 116 (step S412).

The system control apparatus 200 issues an Alloc Spare command andtransmits the data for updating the second spare area locationinformation 133 to the optical disk drive apparatus 204 (step S413).

The optical disk drive apparatus 204 updates the second spare arealocation information 133 stored in the defect management informationmemory 241 based on the data transmitted from the system controlapparatus 200 (step S414).

Through the operations of steps S412 and S414, the second spare area 108becomes available as an added spare area in the optical disk driveapparatus 204. In the example illustrated in FIG. 1, the second sparearea 108 includes #4 spare sector 122 to #6 spare sector 120. The numberof spare sectors included in the second spare area 108 is not limited to3. The second spare area 108 may include any number of spare sectors.

The file structure operation section 211 transmits the data for thespace bit map area 113 stored in the file structure memory 221 to theoptical disk drive apparatus 204 (step S415).

The data write control section 235 updates the space bit map area 113 byrecording the data transmitted from the system control apparatus 200 inthe space bit map area 113 (step S416).

The defective sector operation section 234 records in the defectmanagement information area 101 the data which is stored in the defectmanagement information memory 241 by the method described above in theprocedure of the exemplary format operation (step S417).

As described above, in the data write operation for recording a file onthe optical disk, it is possible to extend the first spare area 102(i.e., to additionally allocate the second spare area 108) based on thestatus of consumption of the first spare area 102. Thus, it is possibleto increase the reliability of data recording without performing aninitialization operation.

When recording a file on the optical disk, the file structure operationsection 211 may determine locations where data can be recorded,sequentially starting from a sector with the least LSN. In this way,data is recorded preferentially from the inner periphery of the opticaldisk, so that data is less likely to be recorded in an area to which thesecond spare area is extended, whereby it is possible to easily extendthe spare area without moving files.

While an optical disk including the first spare area has been describedin the above embodiment, the present invention may alternatively beapplied to an optical disk in which the first spare area does not exist.For example, it is possible not to allocate the second spare area whenthere is no defective sector, while additionally allocating the secondspare area when there occurs a defective sector. With such a defectmanagement method, it is possible to obtain effects similar to thoserealized in the above-described embodiment.

Next, a method for determining whether or not it is necessary to extendthe first spare area 102 will be described with reference to FIGS. 1, 2and 6A-6C. This method may alternatively be applied to a determinationof whether or not it is necessary to extend the second spare area 108.

FIGS. 6A-6C are protocol charts illustrating an procedure of anoperation of determining whether or not it is necessary to extend thefirst spare area 102. This operation is performed by the optical diskdrive apparatus 204 and the system control apparatus 200.

FIG. 6A illustrates an operation performed when the optical disk isinserted into the optical disk drive apparatus 204.

As described above, when the optical disk is inserted into the opticaldisk drive apparatus 204, the file structure operation section 211reproduces the volume structure area 103 and the basic file structurearea 104 and instructs the data read control section 236 to transmit thereproduced data to the file structure memory 221 (step S402 in FIG. 5).

The file structure operation section 211 analyzes the basic filestructure based on the data transmitted to the file structure memory221. As a result, the file structure operation section 211 calculatesthe size of area in the logical volume space 100 b that is available forrecording based on the data reproduced from the space bit map area 113.The size of area is calculated by, for example, summing the number ofsectors in the unallocated area 107. The calculation result is stored inthe spare area information memory 224.

The file structure operation section 211 issues a Get Spare Info commandto the optical disk drive apparatus 204 in order to inquire as to theremaining amount of the first spare area 102 (step S601).

The remaining spare area amount detection section 233 calculates theremaining amount of the first spare area 102 (e.g., the number of sparesectors that are available for replacement) by the method as describedabove in the description of the format operation, and the remainingspare amount reporting section 231 reports the calculation result to thesystem control apparatus 200 (step S602). The information indicating theremaining amount of the first spare area 102 is stored in the spare areainformation memory 224.

The spare area extension determination section 215 calculates the ratio(A/B) of the remaining amount (A) of the first spare area 102 withrespect to the size of area (B) in the logical volume space 100 b thatis available for recording, and determines that the first spare area 102should be extended if the ratio (A/B) is less than a predetermined ratio(e.g., 0.5%) (step S603).

The determination operation illustrated in FIG. 6A is performed uponinsertion of the optical disk before data is recorded thereon. Thedetermination operation has features that the procedure of thedetermination operation is simple and that the implementation of thedetermination operation is easy.

FIG. 6B illustrates an operation performed when recording a file. In theoperation illustrated in FIG. 6B, when a file is recorded on the opticaldisk, it is determined before recording the file whether or not it isnecessary to extend the first spare area 102. Such a determination isperformed based on the size of the data to be recorded and the remainingamount of the first spare area 102.

The file structure operation section 211 stores the data to be recordedon the optical disk in the data memory 223 and calculates the size ofthe data. The calculation result is stored in the spare area informationmemory 224.

The file structure operation section 211 issues a Get Event StatusNotification command to the optical disk drive apparatus 204 in order toinquire as to the status of consumption of the first spare area 102(step S604).

The remaining spare area amount detection section 233 calculates theremaining amount of the first spare area 102 by the method describedabove in the description of the format operation. If the remainingamount of the first spare area 102 is less than a predetermined size(e.g., 1 MB), the remaining spare amount reporting section 231 reportsshortage information indicating the shortage of the first spare area 102to the system control apparatus 200 (step S605). The shortageinformation is stored in the spare area information memory 224.

The spare area extension determination section 215 determines whether ornot the first spare area 102 should be extended based on the size of thedata to be recorded and the shortage information (step S606). Forexample, when the size of the data to be recorded is greater than theremaining amount of the first spare area 102, the spare area extensiondetermination section 215 determines that the first spare area 102should be extended.

With the determination operation illustrated in FIG. 6B, it is possibleto allocate the spare area according to the size of the file to berecorded. Therefore, the operation has features that it is possible toreasonably ensure the reliability of data recording, assuming that thefrequency of occurrence of defective sectors is statisticallysubstantially constant.

FIG. 6C illustrates an operation performed in data transmission.

When a file is recorded on the optical disk, the data of the file isdivided into a plurality of data portions. For example, when data havinga size of 1 MB is recorded on the optical disk, the data is divided intoa plurality of data portions each having a size of 32 kB.

A Write command is issued for each of the data portions. As a result,each of the data portions is transmitted from the system controlapparatus 200 to the optical disk drive apparatus 204.

In the operation illustrated in FIG. 6C, it is determined whether or notthe first spare area 102 should be extended each time a data portion istransmitted.

The file structure operation section 211 issues a Write command to theoptical disk drive apparatus 204 for each of the data portions (stepS607).

The data write control section 235 records the data portion transmittedfrom the system control apparatus 200 in a predetermined sector, andwhen a defective sector is detected, the defective sector operationsection 234 performs a replacement operation for the defective sector.

When the recording operation for the data portions is completed, theremaining spare amount reporting section 231 reports Status informationindicating the execution result of the Write command to the systemcontrol apparatus 200 (step S608). The Status information includesinformation indicating the number of defective sectors which haveoccurred during the data transmission.

The command status operation section 216 receives the Status informationfrom the optical disk drive apparatus 204, and stores the informationindicating the number of defective sectors which have occurred duringthe data transmission in the spare area information memory 224. Thespare area extension determination section 215 determines whether or notany defective sector has occurred during the data transmission based onthe information stored in the spare area information memory 224. If anydefective sector has occurred, the spare area extension determinationsection 215 determines that the first spare area 102 should be extendedby the number of defective sectors (step S609).

The determination operation illustrated in FIG. 6C has a feature that itis possible to effectively utilize the area of the optical disk that isavailable for recording. This is because the spare area can be extendedeach time a defective sector is detected, whereby the size of the areawhich is allocated as a spare area can be reduced.

In the above-described determination operation, the report by theremaining spare amount reporting section 231 of the remaining amount ofthe spare area to the system control apparatus 200 may be done in anyform. For example, the remaining amount of the spare area may berepresented in the form of flags or in the form of a remaining amountvalue.

Next, a method for extending the first spare area 102 and the secondspare area 108 will now be described in detail with reference to FIGS.1, 2 and 7.

FIG. 7 is a protocol chart illustrating a procedure of an operation ofextending the first spare area 102 and a second spare area 108. Thisoperation is performed by the optical disk drive apparatus 204 and thesystem control apparatus 200.

When it is determined by the spare area extension determination section215 that the first spare area 102 (or the second spare area 108) shouldbe extended, the spare extension area detection section 212 determinesthe area to be allocated as an additional spare area based on the secondspare area location information 143 stored in the file structure memory221 (step S701).

When allocating the second spare area 108 for the first time, the secondspare area 108 may be allocated in any area in the logical volume space100 b. However, when contiguous data of a large file size such as audiovideo data (AV data) is recorded on the optical disk, it is necessary toallocate a larger contiguous unallocated area 107. Therefore, whenallocating the second spare area 108 for the first time, the secondspare area 108 is desirably allocated starting from the end of thelogical volume space 100 a.

The spare sectors included in the second spare area 108 are used in anorder such that spare sectors assigned with larger LSNs are used beforethose assigned with smaller LSNs. In other words, the defective sectorsare replaced by the spare sectors in descending order of the LSNsassigned to the spare sectors.

When the second spare area 108 is extended, the second spare area 108 isextended in a direction along which the LSN decreases. When the secondspare area 108 is extended, the area allocated as an additional sparearea may be an area contiguous with the second spare area 108 or an areaseparated from the second spare area 108.

The file structure operation section 211 determines whether or not thearea to be allocated as an additional spare area is unallocated based onthe space bit map information stored in the bit map memory 222 (stepS702). If the area is unallocated, the process proceeds to step S704,and if not, the process proceeds to step S704 via step S703. This isbecause when the area to be allocated as an additional spare area is notunallocated (i.e., when data is already recorded in the area), it isnecessary to move the data to another location before the area can beused as an additional spare area.

The file moving operation section 213 performs a file moving operation(step S703). In particular, the file moving operation section 213examines the file structure of all the files on the optical disk todetermine the data recorded in the area. Then, the file moving operationsection 213 uses the space bit map information to search for an area towhich it is possible to move the data which has already been recorded inthe area to be allocated as an additional spare area, move the dataaccording to the attribute of the data, and update the information ofthe file structure managing the moved data (step S703). In this way, anadditional spare area is allocated.

Although not shown in FIG. 7, the spare extension area allocationsection 214 instructs the optical disk drive apparatus 204 to examinewhether or not there is any defective sector in the area to be allocatedas an additional spare area. When there is any defective sector in thearea, the spare extension area allocation section 214 instructs thespare extension area detection section 212 to increase the size of theadditional area, and returns the control of the process to step S701.Thus, the process is performed again from step S701.

When there is no defective sector in the area to be allocated as anadditional spare area, the spare extension area allocation section 214issues a Write command and transmits data for updating the file entryarea 116 stored in the file structure memory 221 (step S704).

The data write control section 235 records the data transmitted from thesystem control apparatus 200 in the file entry area 116 (step S705). Asa result, the second spare area location information 143 recorded in thefile entry area 116 is updated.

The spare extension area issue section 217 issues an instruction toextend the spare area by using an Alloc Spare command. Specifically, thespare extension area issue section 217 issues an Alloc Spare command andtransmits data for updating the second spare area location information133 to the optical disk drive apparatus 204 (step S706).

The data write control section 235 updates the second spare arealocation information 133 stored in the defect management informationmemory 241 based on the data transmitted from the system controlapparatus 200 (step S707).

Thus, when any data is recorded in the area to be allocated as anadditional spare area, the data recorded in the area to be allocated asan additional spare area is moved to another area by analyzing theinformation of the file structure. In this way, the spare area can beextended even when data has been recorded in an area into which a sparearea is to be extended.

When there is any defective sector in an area to be allocated as anadditional spare area, the size of the additional spare area isincreased according to the number of the defective sectors. Thus, it ispossible to reliably ensure a spare area of a required size.

Next, countermeasures which can be taken when the second spare arealocation information 143 managed by the system control apparatus 200 andthe second spare area location information 133 managed by the opticaldisk drive apparatus 204 are not consistent with each other and a methodfor recovering the inconsistency between the information 143 and 133will be described.

In FIG. 1, it is assumed that sector a (sector 117) in the data area 105has been detected as a defective sector, and the sector 117 has beenreplaced by the #4 spare sector 122. In such a case, the #4 spare sector122 is specified by two LSNs. The first LSN is one of the LSNs which aresequentially assigned in the volume space 100 a starting from thebeginning of the volume space 100 a (herein, LSN=n). The second LSN isthe LSN which is assigned to the replaced defective sector 117 (herein,LSN=m).

When the second spare area location information 143 managed by thesystem control apparatus 200 and the second spare area locationinformation 133 managed by the optical disk drive apparatus 204 are notconsistent with each other, the system control apparatus 200 maypossibly issue a Write command to the sector whose LSN is n. When therecording operation is performed, the data recorded in the #4 sparesector 122 is overwritten. As a result, data of the file named “File-a”is destroyed.

In order to avoid the fatal incident of destroying the data of a file,the optical disk drive apparatus 204 recognizes the sectors included inthe second spare area 108 by referencing the second spare area locationinformation 133. When it is requested to record data in a sectorincluded in the second spare area 108, the optical disk drive apparatus204 reports to the system control apparatus 200 error informationindicating prohibition of a recording request to the second spare area108, without performing a recording operation corresponding to therequest. In this way, it is possible to prevent data of a file frombeing destroyed due to the inconsistency between the second spare arealocation information 133 and the second spare area location information143.

When the system control apparatus 200 receives the error information,the system control apparatus 200 preferably performs an operation ofmaking the second spare area location information 133 consistent withthe second spare area location information 143. For example, asdescribed above in the description of the format operation, the systemcontrol apparatus 200 may obtain the second spare area locationinformation 133 based on the information reproduced from the defectmanagement information area 101, and update the second spare arealocation information 143 recorded in the file entry area 116 based onthe location information 133, while updating the space bit map stored inthe bit map memory 222 based on the location information 143.

Before updating the second spare area location information 143, it ispreferred to confirm that an area which is newly registered in the fileentry as the second spare area 108 is not being used for any purposeother than a spare area, as described above in the description of theoperation of extending a spare area. Such confirmation can be done byexamining all the file structures.

The above-described example where the location information 133 and 143are not consistent with each other is an exemplary case where the sizeof the second spare area 108 recorded in the defect managementinformation area 101 is greater than the size of the second spare area108 recorded in the file entry area 116.

It is possible to detect the inconsistency between the locationinformation 133 and 143 and to make the location information 133 and 143consistent with each other also when the size of the second spare area108 recorded in the defect management information area 101 is less thanthe size of the second spare area 108 recorded in the file entry area116.

For example, as a start-up operation for the system control apparatus200, the system control apparatus 200 may obtain the locationinformation 133 based on the data reproduced from the basic filestructure area 104, while obtaining the location information 143 bymaking an inquiry for the spare area information. By comparing thelocation information 133 and the location information 143 with eachother, it is possible to detect the inconsistency between the locationinformation 133 and 143.

When the inconsistency between the location information 133 and 143 isdetected, the system control apparatus 200 instructs the optical diskdrive apparatus 204 to correctly update the second spare area locationinformation by using an Alloc Spare command.

(Embodiment 2)

In Embodiment 2, an example where the second spare area 108 is allocatedoutside the volume space 100 a will be described.

In Embodiment 2, an information recording/reproduction system 1 b isused. The configuration of the information recording/reproduction system1 b is the same as that of the information recording/reproduction system1 a illustrated in FIG. 2, and thus will not be described below.

Each of the system control apparatus 200 and the optical disk driveapparatus 204 is connected to the I/O bus 203 via a SCSI or ATAPIinterface. Commands and data are exchanged between the system controlapparatus 200 and the optical disk drive apparatus 204.

The system control apparatus 200 and the optical disk drive apparatus204 may be an integrally-formed single apparatus. In such a case, theinterface between the system control apparatus 200 and the optical diskdrive apparatus 204 may be a simplified dedicated interface.

FIG. 8 is a diagram illustrating a structure of the data recording area100 of an optical disk according to an embodiment of the presentinvention. In FIG. 8, reference numeral 181 denotes the state of theoptical disk after the format operation, reference numeral 182 denotesthe state of the optical disk after a data write operation of recordinga file named “File-a” on the optical disk, and reference numeral 183denotes the state of the optical disk after a data write operation ofrecording a file named “File-b” on the optical disk.

FIG. 9 is a protocol chart illustrating a data write operation forrecording a file on an optical disk.

The data write operation illustrated in FIG. 9 includes: step S807 ofcalculating the status of consumption of a spare area; step S809 ofdetermining additional allocation of a spare area based on thecalculated status of consumption; step S811 of making a part of thevolume space available as a spare area; and step S817 of registering thearea made available as a spare area. These steps are the same as thosein the data write operation described in Embodiment 1.

A data write operation of recording a file (File-a) on the optical diskwhen the optical disk is in the state denoted by reference numeral 181in FIG. 8 will now be described. Through this data write operation, thestate of the optical disk transitions from the state denoted byreference numeral 181 in FIG. 8 to the state denoted by referencenumeral 182 in FIG. 8. Through this data write operation, a second sparearea 153 is newly allocated. The state of the optical disk denoted byreference numeral 181 is the same as that illustrated in FIG. 4.

When the optical disk is inserted into the optical disk drive apparatus204, as a start-up operation for the optical disk drive apparatus 204,the remaining spare area amount detection section 233 obtainsinformation which indicates the status of consumption of the first sparearea 102 (step S801).

For example, the remaining spare area amount detection section 233 mayobtain information indicating the status of consumption of the firstspare area 102 by referencing the spare area full flag 132. The firstfull flag 138 being set indicates that all of the spare sectors in thefirst spare area 102 are used (i.e., no spare sector is available forreplacement in the first spare area 102).

In the first spare area 102, the spare sectors are sequentially usedstarting from the spare sector that is assigned the largest physicalsector number. In other words, the defective sectors are replaced by thespare sectors in descending order of the physical sector numbersassigned to the spare sectors. Such an order in which the spare sectorsare used is also used in the second spare area 108.

The remaining spare area amount detection section 233 may alternativelyretrieve one of the replacement entries recorded in the defectmanagement information area 101 that has the smallest locationinformation (e.g., the physical sector number) of a spare sector so asto obtain the information indicating the status of consumption of thefirst spare area 102 based on the location information of the sparesector in the retrieved replacement entry. Thus, the remaining sparearea amount detection section 233 can know the amount of spare sectoravailable in the first spare area 102 based on the location informationof the spare sector in the retrieved replacement entry and the size ofthe first spare area 102. In the example illustrated in FIG. 8, the sizeof the first spare area 102 is predetermined. Therefore, the remainingspare area amount detection section 233 can know the amount of sparesectors available in the first spare area 102 based on the locationinformation of the spare sector in the retrieved replacement entry.

Thus, the information indicating the status of consumption of the firstspare area 102 may be either the first full flag 138 or the amount ofspare sector available in the first spare area 102.

As a start-up operation for the system control apparatus 200, the filestructure operation section 211 issues a Read command to the opticaldisk drive apparatus 204 (step S802).

The data read control section 236 reproduces data recorded in the volumestructure area 103 and the basic file structure area 104 according tothe address specified by the Read command, and returns the reproduceddata to the system control apparatus 200 (step S803).

The file structure operation section 211 receives the data reproducedfrom the optical disk drive apparatus 204, and analyzes the basic filestructure based on the reproduced data (step S802).

The file structure operation section 211 issues a Write command andtransmits data of the file (File-a) to the optical disk drive apparatus204 (step S804).

The data write control section 235 records the data transmitted from thesystem control apparatus 200 in the data area 105 and the file structurearea 106 (step S805).

When any defective sector is detected in the data write operation instep S805, the defective sector operation section 234 performs areplacement operation of replacing the defective sector by a sparesector in the first spare area 102 (step S806).

The remaining spare area amount detection section 233 obtainsinformation indicating the status of consumption of the first spare area102 based on the information of the defect management information memory241 which has been updated in step S806 (step S807).

When the first spare area 102 has been exhausted, the remaining spareamount reporting section 231 notifies the system control apparatus 200of the information indicating that the first spare area 102 has beenexhausted (step S810). Such a notification can be made by, for example,by returning to the system control apparatus 200 “Recovered Error” asStatus information to the Write command transmitted in step S804.

The spare area extension determination section 215 recognizes theexhaustion of the first spare area 102 via the command status operationsection 216, and determines to allocate the second spare area 153 in anarea in the outermost periphery of the data recording area by reducingthe volume space 100 a (step S809).

Since the second spare area is allocated in an area in the datarecording area 100 whose PSN is largest, the second spare area locationinformation 133 is represented only by the PSN of the first sectorincluded in the second spare area 108, for example.

The spare extension area allocation section 214 instructs the opticaldisk drive apparatus 204 to update the volume structure areas 103 and109 and the basic file structure area 104 by using a Read command and aWrite command in order to allocate an area for allocating the secondspare area 153 in the area on the outer periphery side following thevolume space 100 a by reducing the volume space 100 a (step S811).

The data write control section 235 and the data read control section 236update the volume structure areas 103 and 109 and the basic filestructure area 104 according to these commands (step S812).

The details of the update operation illustrated in steps S811 and S812will be described later with reference to FIG. 11.

The spare extension area issue section 217 instructs the optical diskdrive apparatus 204 to register the newly-allocated area as the secondspare area 153 by using an Alloc Spare command (step S813). A FormatUnit command may alternatively be used instead of an Alloc Sparecommand.

The spare area allocation section 232 recognizes that a second sparearea has not been allocated by using the second spare area locationinformation 133 stored in the defect management information memory 241,updates the second spare area location information 133 stored in thedefect management information memory 241 so as to newly allocate thesecond spare area 153 based on an Alloc Spare command (or a Format Unitcommand), and resets the second full flag 139 for the second spare area153 (step S814). Since the second spare area 153 is allocated outsidethe volume space, the sectors in the second spare area 153 do not haveLSNs.

The defective sector operation section 234 records the updated defectmanagement information 130 stored in the defect management informationmemory 241 in the defect management information area 101 (step S817).Such recording is performed immediately after step S813 or when there isno data recording instruction from the system control apparatus 200 fora predetermined period of time (e.g., 5 seconds).

Thus, the optical disk drive apparatus 204 and the system controlapparatus 200 cooperate with each other to additionally allocate thesecond spare area 153, whereby it is possible to increase thereliability of data recording.

The second spare area 153 may be allocated in an area separated from thefirst spare area 102 or in an area contiguous with the first spare area102.

For example, the second spare area 153 is allocated in an area includinga sector which is assigned a physical sector number that is larger thanthat of any sector in the first spare area 102. When the second sparearea 153 includes a plurality of spare sectors, the defective sector isreplaced by a corresponding one of the spare sectors in descending orderof the physical sector numbers assigned to the spare sectors.

Moreover, as indicated by reference numeral 182 in FIG. 8, the volumespace 100 a is re-configured to include the volume structure area 103,the basic file structure area 104, the data area (File-a) 105, the filestructure area (File-a) 106, an unallocated area 151 and a volumestructure area 152, while holding the files that have already beenrecorded on the optical disk.

In this way, the volume space 100 a is re-configured so that the secondspare area 153 is allocated outside the volume space 100 a. Thiseliminates the need for the operation for avoiding the inconsistencybetween the second spare area location information 133 recorded in thedefect management information area 101 and the second spare arealocation information 143 recorded in the file entry area 116, as thatdescribed in Embodiment 1 above.

Moreover, in Embodiment 2, it is not necessary to record the locationinformation of the second spare area in the basic file structure area104. This eliminates the need to provide a special data structure forthe file system, whereby when reusing an optical disk on which a secondspare area has once been allocated, it is possible to reuse the opticaldisk, after a logical format, not only for the file system described inthe present embodiment but also for a more generally-used FAT filesystem which is used in, e.g., MS-DOS.

The size of the second spare area 153 may be determined according to thestatus of consumption of the first spare area 102. For example, if instep S810 the remaining spare amount reporting section 231 reports theexhaustion of the first spare area 102 to the system control apparatus200 when the size of the spare sector in the first spare area 102available for replacement has decreased to be 1 MB or less, then thesecond spare area 153 may be allocated by blocks of 1 MB.

When ECC (Error Correction Code) is arranged by blocks of 16 sectors,one ECC block includes 16 sectors. Then, the replacement of defectivesectors may be performed by ECC blocks, rather than by blocks ofsectors. By performing the replacement operation by ECC blocks, it is nolonger necessary to re-calculate ECCs, whereby therecording/reproduction system can be simplified.

Preferably, the smallest unit by which the second spare area can beextended is predetermined. For example, it may be determined to extendthe second spare area by blocks of 32 ECC blocks (1 MB). In such a case,as compared to a case where the spare area is extended by blocks of 2 to3 sectors, it is possible to reduce the frequency of exhaustion of sparearea. Moreover, by extending the second spare area by ECC blocks, it ispossible to facilitate the replacement of defective sectors by ECCblocks.

The descriptors defined in the ECMA167 standard which are recorded inthe volume structure area 103, the basic file structure area 104, thefile structure area (File-a) 106 and the volume structure area 152 maybe recorded on the optical disk in a dispersed arrangement.

A data write operation of recording a file (File-b) on the optical diskwhen the optical disk is in the state denoted by reference numeral 182in FIG. 8 will now be described. Through this data write operation, thestate of the optical disk transitions from the state denoted byreference numeral 182 in FIG. 8 to the state denoted by referencenumeral 183 in FIG. 8. Through this data write operation, an additionalspare area is allocated in an area which is contiguous with the secondspare area 153 which has already been allocated. As a result, a secondspare area 158 is allocated which is obtained by extending the secondspare area 153.

Thus, the second spare area 153 can be extended in a direction alongwhich the physical sector number decreases.

The data write operation of recording the file (File-b) on the opticaldisk is also performed according to steps S801-S817 illustrated in FIG.9.

The operations of steps S801-S803 are the same as those described above,and thus will not be described below.

The file structure operation section 211 issues a Write command andtransmits data of the file (File-b) to the optical disk drive apparatus204 (step S804).

The data write control section 235 records the data transmitted from thesystem control apparatus 200 in a data area 154 and a file structurearea 155 (step S805).

When any defective sector is detected in the data write operation instep S805, the defective sector operation section 234 performs areplacement operation for replacing the defective sector by the sparesectors in the second spare area 153 (step S806). A replacement entryindicating that the defective sector has been replaced by a spare sectoris generated, and the replacement entry is stored in the defectmanagement information memory 241 before it is recorded in the defectmanagement information area 101.

If all of the spare sectors in the second spare area 153 have beenconsumed, the defective sector operation section 234 sets the secondfull flag 139 of the spare area full flag 132.

The remaining spare area amount detection section 233 obtainsinformation indicating the status of consumption of the second sparearea 153 (step S807). The method for obtaining the informationindicating the status of consumption of the second spare area 153 issimilar to the above-described method for obtaining the informationindicating the status of consumption of the first spare area 102.

When the second spare area 153 is exhausted, the remaining spare amountreporting section 231 notifies the system control apparatus 200 of theinformation indicating that the second spare area 153 has been exhausted(step S810).

The spare area extension determination section 215 recognizes theexhaustion of the second spare area 153 via the command status operationsection 216, and determines to newly allocate an additional spare areain an area which is contiguous with the second spare area 153 (stepS809).

The spare extension area allocation section 214 instructs the opticaldisk drive apparatus 204 to update the volume structure areas 103 and152 and the basic file structure area 104 by using a Read command and aWrite command in order to allocate an area for allocating the additionalspare area by reducing the volume space 100 a (step S811).

The data write control section 235 and the data read control section 236update the volume structure areas 103 and 152 and the basic filestructure area 104 according to these commands (step S812).

The spare extension area issue section 217 instructs the optical diskdrive apparatus 204 to register the newly-allocated area and the secondspare area 153 as the new second spare area 158 (step S813).

The spare area allocation section 232 recognizes that the second sparearea 153 has been allocated by using the second spare area locationinformation 133 stored in the defect management information memory 241,and checks the second full flag 139. Then, the spare area allocationsection 232 updates the second spare area location information 133stored in the defect management information memory 241 so as to extendthe second spare area in a direction along which the physical sectornumber decreases, and when the second full flag 139 for the second sparearea 153 is set, resets the second full flag 139 (step S814). Thus, itis possible to use a spare sector available for replacement in thesecond spare area 158.

The defective sector operation section 234 records the updated defectmanagement information 130 stored in the defect management informationmemory 241 in the defect management information area 101 (step S817).Such recording is performed when there is no data recording instructionfrom the system control apparatus 200 for a predetermined period of time(e.g., 5 seconds).

Thus, by the cooperation of the optical disk drive apparatus 204 and thesystem control apparatus 200, it is possible to extend the second sparearea according to the frequency of occurrence of defective sectors.

FIG. 10 is a protocol chart illustrating a procedure of an operationwhich is performed when an optical disk is inserted into an optical diskdrive apparatus. In this procedure, the status of consumption of thespare area is examined upon insertion of the optical disk. As a result,whether or not it is necessary to allocate an additional spare area isdetermined according to the status of consumption of the spare area.

In the following description made in connection with FIG. 10, the term“spare area” refers to the “first spare area 102”, the “second sparearea 153” or the “second spare area 158” illustrated in FIG. 8.

The file structure operation section 211 issues a Get Spare Info commandto the optical disk drive apparatus 204 in order to inquire as to thestatus of consumption of the spare area (step S821). The file structureoperation section 211 may alternatively use a Read DVD Structure commandinstead of a Get Spare Info command.

The remaining spare area amount detection section 233 obtainsinformation indicating the status of consumption of the spare area (stepS807). The information indicating the status of consumption of the sparearea includes, for example, information indicating the size of area inthe spare area that is available for replacement.

The remaining spare amount reporting section 231 reports the informationindicating the status of consumption of the spare area to the systemcontrol apparatus 200 (step S810).

The spare area extension determination section 215 determines whether ornot to allocate an additional spare area according to the status ofconsumption of the spare area. For example, when the size of area in thespare area that is available for replacement is less than or equal to apredetermined size (e.g., 1 MB), the spare area extension determinationsection 215 determines to newly allocate an additional spare area (stepS809).

The operations of steps S811-S817 illustrated in FIG. 10 are the same asthose of steps S811-S817 illustrated in FIG. 9, and thus will not bedescribed below.

Thus, by the cooperation of the optical disk drive apparatus 204 and thesystem control apparatus 200, it is possible, before recording data, toallocate a spare area having an optimal size according to the status ofconsumption of the spare area.

An operation of updating the volume structure areas 103 and 109 and thebasic file structure area 104 will now be described in detail withreference to FIG. 11. The update operation is performed by the spareextension area allocation section 214. In FIG. 11, each referencenumeral that starts with “S” denotes a step in the update operation.

FIG. 11 illustrates, as indicated by reference numerals 191 and 192, thedata structure of the optical disk in the state denoted by referencenumerals 181 and 182 in FIG. 8, respectively, in greater detail, i.e.,on the descriptor level, which is defined in the ECMA167 standard.

The volume structure area 103 is arranged along the inner periphery ofthe volume space 100 a. A main volume descriptor sequence 161 fordefining the volume space 100 a as a logical space, a logical volumeintegrity descriptor 162 having integrity information of the logicalvolume space 100 a, an anchor volume descriptor pointer indicating thelocation at which to start reading out the volume structure, and a fileset descriptor 164 are recorded in the volume structure area 103.

While a file set descriptor is defined as a file structure according toECMA167, in the example illustrated in FIG. 11, a file set descriptor isdefined as a volume structure for the purpose of discussion.

The volume structure area 109 is arranged in the outermost periphery ofthe volume space 100 a. An anchor volume descriptor pointer 165 and areserve volume descriptor sequence 156 are recorded in the volumestructure area 109.

The basic file structure area 104 includes the space bit map area 113,the file entry area 114, and the root directory area 115. A space bitmap for managing unallocated areas in the logical volume space 100 b isrecorded in the space bit map area 113. The file entry of the rootdirectory is recorded in the file entry area 114. Information of theroot directory is recorded in the root directory area 115.

The spare extension area allocation section 214 retrieves the size andthe location of the unallocated area 107 based on the informationreproduced from the space bit map area 113.

When the unallocated area 107 that is larger than the size of theadditional spare area to be allocated as the second spare area 153exists at the end of the logical volume space 100 b (i.e., a portionalong the outermost periphery of the logical volume space 100 b), thespare extension area allocation section 214 updates the space bit maparea 113 so as to reduce the logical volume space 100 b by the size ofthe additional spare area (step S101).

When there is no unallocated area 107 that is larger than the size ofthe additional spare area, a file moving operation (step S703 in FIG. 7)is performed. As a result, data of a file which has already beenrecorded is moved to another area.

The spare extension area allocation section 214 updates and moves thereserve volume descriptor sequence 156 and the anchor volume descriptorpointer 165 so that the second spare area 153 can be allocated (stepsS102 and S103).

The spare extension area allocation section 214 updates the main volumedescriptor sequence 161 and the logical volume integrity descriptor 162in order to define a reduced logical volume space (steps S104 and S105).

Finally, the spare extension area allocation section 214 updates ananchor volume descriptor pointer 163 in order to activate the updatedvolume structure and the updated file structure (step S106).

Thus, by making a part of the volume space 100 a available, it ispossible to allocate an area in which the second spare area 153 isallocated.

In the information recording medium of the present invention, the volumespace in which user data can be recorded is configured so that thesecond spare area can be additionally allocated. Thus, it is possible todynamically extend the spare area according to the frequency ofoccurrence of defective sectors. As a result, it is possible to ensurethe reliability of data recording without performing an initializationoperation or a re-format operation even when there occurs more defectivesectors than expected.

Since the spare area can be extended according to the frequency ofoccurrence of defective sectors, it is possible to maximize the amountof user data which can be recorded in the logical volume space.

When data is recorded in an area to be allocated as an additional sparearea, the additional spare area can be allocated after moving the datato another area. Thus, it is possible to increase the freedom in thearea where an additional spare area can be allocated.

Various other modifications will be apparent to and can be readily madeby those skilled in the art without departing from the scope and spiritof this invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the description as set forthherein, but rather that the claims be broadly construed.

What is claimed is:
 1. An information recording medium including aplurality of sectors, the information recording medium comprising a datarecording area, the data recording area including: a first spare areahaving a replacement area including a spare sector for replacing adefective area including a defective sector among the plurality ofsectors; a defect management information area in which defect managementinformation for managing the replacement of the defective area includingthe defective sector by the replacement area including the spare sectoris recorded; and a volume space in which user data can be recorded,wherein: each of the sectors in the data recording area is assigned aphysical sector number; in the data recording area, a second spare areahaving a replacement area including a spare sector for replacing adefective area including a defective sector among the plurality ofsectors can be allocated in an area including a sector having a physicalsector number which is larger than a physical sector number assigned tothe spare sector in the first spare area, and the second spare area canbe extended by an ECC block unit in a direction along which the physicalsector number decreases; and the defect management information area hasan area for recording location information which indicates a location ofthe second spare area.
 2. An information recording medium according toclaim 1, wherein the ECC block unit comprises 32 ECC blocks.
 3. Aninformation recording method for recording information on an informationrecording medium including a plurality of sectors, the informationrecording medium comprising a data recording area, the data recordingarea including: a first spare area having a replacement area including aspare sector for replacing a defective area including a defective sectoramong the plurality of sectors; a defect management information area inwhich defect management information for managing the replacement of thedefective area including the defective sector by the replacement areaincluding the spare sector is recorded; and a volume space in which userdata can be recorded, wherein: in the data recording area, a secondspare area having a replacement area including a spare sector forreplacing a defective area including a defective sector among theplurality of sectors can be extended; and each of the spare sector inthe first spare area and the spare sector in the second spare area isassigned a physical sector number, and the physical sector numberassigned to the spare sector in the first spare area is smaller than thephysical sector number assigned to the spare sector in the second sparearea, the information recording method comprising the steps of: (a)obtaining information which indicates a status of consumption of thesecond spare area; (b) determining whether or not to extend, in the datarecording area, the second spare area having a replacement areaincluding a spare sector for replacing a defective area including adefective sector among the plurality of sectors according to theinformation which indicates the status of consumption of the secondspare area; and (c) when the second spare area is extended, extendingthe second spare area by an ECC block unit in a direction along whichthe physical sector number decreases.
 4. An information recording methodaccording to claim 3, wherein the ECC block unit comprises 32 ECCblocks.
 5. An information recording/reproduction system for aninformation recording medium including a plurality of sectors, theinformation recording medium comprising a data recording area, the datarecording area including: a first spare area having a replacement areaincluding a spare sector for replacing a defective area including adefective sector among the plurality of sectors; a defect managementinformation area in which defect management information for managing thereplacement of the defective area including the defective sector by thereplacement area including the spare sector is recorded; and a volumespace in which user data can be recorded, wherein: in the data recordingarea, a second spare area having a replacement area including a sparesector for replacing a defective area including a defective sector amongthe plurality of sectors can be extended; and each of the spare sectorin the first spare area and the spare sector in the second spare area isassigned a physical sector number, and the physical sector numberassigned to the spare sector in the first spare area is smaller than thephysical sector number assigned to the spare sector in the second sparearea, the information recording/reproduction system comprising: aremaining spare area amount detection section for obtaining informationwhich indicates a status of consumption of the second spare area; aspare area extension determination section for determining whether ornot to extend, in the data recording area, the second spare area havinga replacement area including a spare sector for replacing a defectivearea including a defective sector among the plurality of sectorsaccording to the information which indicates the status of consumptionof the second spare area; and a spare extension area allocation sectionfor, when the second spare area is extended, extending the second sparearea by an ECC block unit in a direction along which the physical sectornumber decreases.
 6. An information recording/reproduction systemaccording to claim 5, wherein the ECC block unit comprises 32 ECCblocks.